Effect of resin preparation, heat-pretreatment of bovine and fish-gelatin solutions (20%, w/w) containing 25% glycerol (based on protein) at different temperatures (70 and 90oC) for various time (1, 2 and 3 h) prior to semi-drying, on the properties of resulting films was investigated. Tensile strength (TS) and elastic modulus of the films increased, whereas the elongation at break (EAB) decreased when resin was prepared with increasing heating temperature (p<0.05). Resin prepared by using heat-pretreatment for 2 h yielded the films with the lowest EAB (p<0.05), while an increased EAB was found as resin was prepared from solution heat-pretreated for 3 h, regardless of heating temperature used (p<0.05). Heat-pretreatment at high temperature (90oC) and long time (3 h) significantly resulted in degradation of gelatin molecules, leading to loss of films strength. However, heat-pretreatment condition in resin preparation step had no marked effect on water vapor permeability (WVP), color and transparency of resulting films. Films from bovine gelatin had the higher EAB and WVP, compared with fish-gelatin film. The former had the lower L* and a*-values, but possessed the higher b*-value than the latter. Gelatin films exhibited the potential barrier property to UV light. Thus, heat-pretreatment condition for resin preparation had the direct effect on the properties, especially mechanical properties, of resulting films fabricated by thermo-compression molding.